This invention relates to multilamp photoflash units and, more particularly, to an improved construction therefor.
Previous multilamp photoflash units having a horizontally disposed base are represented by the eletrically fired fourlamp array referred to as a flash cube, such as described in U.S. Pat. No. 3,327,105, the percussively ignited four-lamp array referred to as a magicube, such as described in U.S. Pat. No. 3,730,669, and the electrically sequenced ten lamp array referred to as a flashbar, such as described in U.S. Pat. No. 3,857,667. In each of these arrays, the lamps are supported from a generally horizontal plastic base member with the tubular lamp envelopes oriented vertically. Enclosure of the package construction is provided by a transparent plastic cover member having four vertical sidewalls and a horizontal top wall. A multicavity reflector assembly is disposed about the lamps, and then the transparent cover member is placed over the array of lamps and reflectors and attached to the base member so as to provide an enclosed unit. Attachment of the plastic cover to the plastic base member is accomplished by ultrasonically welding the periphery of the cover member about a lip formed along the outer edges of the base member.
Another type of currently marketed photoflash unit, referred to as a flipflash, comprises a vertically planar array of eight or ten lamps which are ignited by sequentially applied high-voltage firing pulses. The overall construction of the flipflash unit comprises a substantially planar rear housing member and a front housing member in a form of a rectangular concavity, both housing members being formed of a plastic material. Sandwiched between the front and rear housing members, in the order named, are the flashlamps, a multi-cavity reflector assembly, a printed circuit board, and an indicia sheet. According to one embodiment, such as described in U.S. Pat. No. 4,047,015, the front and rear housing members are attached together by inerlocking latch means molded in the edges thereof. Use of integrity, as twisting the array or dropping the array several feet onto a hard surface was found to be sufficient to break it open. Accordingly, the seam about the adjoining peripheries of the front and rear housing members is also ultrasonically welded together. In another embodiment of the flipflash array, for example as described in U.S. Pat. No. 4,133,023, the front and rear housing members are joined solely by the welded seam about their peripheries.
According to another embodiment of a planar array of eight flashlamps, for example, as illustrated in German Offenlegungsschrift No. 2629041, published Jan. 27, 1977, the unit has a bathtub-shaped rear housing member, and a substantially planar transparent cover member. The planar cover is attached to the rear housing means by two posts projecting from the central portion of the cover in the upper and lower halves thereof, normal to the plane of the cover, which fit into and pass through respective openings in a pair of inwardly protruding bosses in the rear housing member. The ends of the posts projecting through the back of the rear housing are then reshaped with heat to form retaining lugs, or rivet heads. The perimeter of the rear housing and planar cover is unsealed except for small mechanical latches at each end provided by the fit of small cover projections into recesses in the rear housing. These latches are easily opened by twisting or dropping the array.
A copending patent application Ser. No. 072,257, filed concurrently herewith and assigned to the present assignee, describes a more compact, cost-efficient photoflash unit construction which comprises a plurality of electrically ignitable flashlamps disposed in a linear array along a strip-like printed circuit board. The assembly comprising the lamps mounted on the printed circuit strip is located within the longitudinal channel of an elongated housing member having outer flanges with reflective surfaces adjacent to the lamps. A light-transmitting cover panel is mounted to the housing member so as to enclose the flashlamps in the channel. In assembling the front cover to the rear housing member, which are both plastic, the peripheral surfaces of the cover panel facing the housing member are juxtaposed with a metalized reflective coating on the surfaces of the outer flanges of the housing member facing the panel. As a result, direct attachment of the cover panel to the integral rear housing-reflector member by ultrasonic welding about the joining peripheries of the two members is not consistent with the objective of a low-cost, compact, materials-efficient array. This is due to the metalized coating on the reflective outer surfaces of the housing member which prevents reliable welding. In order to utilize selective masking of the reflective areas of the housing for providing a welding surface or ledge, additional plastic materials, both cover and rear housing, would be necessary to increase the width of the product.